1. Field of the Invention
The present invention relates to antennas and more specifically to a system and method to utilize a conducting enclosure as a highly efficient electrically small antenna.
2. Description of the Prior Art
Ultra-wideband (UWB) systems are in great demand for precision tracking, radar, and communications. A commercially successful UWB system must be both small and very low power. Similarly, there is great interest at present in “smart dust,” miniature sensors, and other nano-devices that can wirelessly transmit data, positioning signals, or radar signals using very low power signals and utilizing wavelengths that may be much larger than the device itself. Highly efficient, electrically small antennas are a necessity for UWB systems, smart dust, nano-devices, and numerous other commercial and government applications.
Prior art efficient antennas commonly are on the order of a half-wavelength long for a dipole or a quarter-wavelength long for a monopole. For ultra-wideband (UWB) operation in the 3.1–10.6 GHz, a 5.3 cm dipole or a 2.6 cm monopole are called for (5.7 GHz center frequency). These antennas may be small enough for some applications. For other applications, even smaller antennas may be required. Efficient quarter to half wave antennas that operate in the upper VHF band or UHF band (for instance from 100 MHz on up) must be significantly larger than analogous microwave antennas. This is too large for many potential applications. In general however, no matter the application, there is always a need to make antennas smaller and less obtrusive while remaining efficient. Existing small VHF/UHF UWB antennas tend to be very inefficient including large current radiators, and resistively loaded antennas. Antennas smaller than a quarter-wavelength are usually referred to as electrically small antennas. In prior art, electrically small antennas are prone to be inefficient, particularly when significantly smaller than a quarter-wavelength.
In view of the foregoing, there is a great need for an efficient, electrically small UWB antenna for positioning, smart dust, nano-devices, and other applications. There is a further need for a method to effect efficient UWB transmissions from electrically small enclosures. Additionally, there is a need for an antenna apparatus that transcends traditionally accepted bounds of antenna size versus performance.